In reply to Euan McKendrick:
I've done Font trips all through the year.
If you get a dry period in November, you can get great conditions which are ideal if you are going to try and project hard (for you) problems. The friction can be night and day compared to warmer months.
But the rock will be much slower to dry than during the summer. We were there over New Year a few years ago. We waited until there was a decent weather window before we booked last minute tickets and traveled. It made our trip shorter but we arrived and climbed on our first day. We met people who had been there for 3 weeks and this was their first day of being able to climb!
If I was going with a mixed ability group who wanted to try different things or do circuits, I would wait for warmer months instead.